Washington diners are familiar with fusion cooking, but how many have tried “conjecture cuisine”? That’s essentially what chef Guillermo Pernot is serving at Cuba Libre Restaurant & Rum Bar—the fourth rendition of his lively Philadelphia Nuevo Latino spot—which opened last week in DC’s Penn Quarter. The menu, as Pernot explains it, is formed around the question “What would have happened to Cuban cuisine if Castro hadn’t come into power?” His answer: Dishes such as fricase de pollo, a classic Cuban chicken casserole with international touches such as Spanish Manzanilla olives and goat-cheese fondue.

Some starters—divided into small plates, ceviches, soups, salads, and shareable “favoritos”—are semi-traditional, such as the guacamole with pineapple and crisp plantain chips inspired by Pernot’s Cuban mother-in-law. Others, such as a ceviche of Maryland crab with smoked cheddar, tomatillos, and candied-peanut salsa, venture into a more experimental realm. The latter is one of five specialty ceviches on the menu from Pernot’s James Beard Award-winning cookbook, ¡Ceviche!, and one of the dishes designed with Washington’s tastes and local ingredients in mind. Discerning between the clásico and nuevo is easier when it comes to the entrées, which separate the likes of traditional ropa vieja (aromatic stewed, shredded brisket) from a seafood paella fashioned with black “forbidden rice,” chipotle aïoli, and a minty “mojito” salsa verde.

While the plates have modern touches, Cuban-born architect Carlos Sobrin designed the space as an Old Havana street scene. Wrought-iron fences separate the 170-seat dining area from a cobblestone path that leads to the kitchen. Balconies jut from the walls, which are cracked and stained to mimic Cuban building facades.

The 50-seat bar is made of beige wood taken from Havana’s Hotel Nacional. Diners can choose from 13 mojitos, which range from an old-school white-rum version made with Cuban mint and sugarcane juice, to one flavored with roasted pineapple and another with beets and basil. Sweeteners, juices, and fruit purées for the cocktails—which also include coladas, caipirinhas, and pisco sours—are made in a bar kitchen upstairs.

Pernot sees this newcomer finding a distinct niche in Washington’s restaurant scene in the hands of executive chef Jason Kaufman, who was imported from the Orlando Cuba Libre (there’s another one in Atlantic City). “It’s not just the cuisine that will be different,” Pernot says. “It will be the bar, the music. It all creates its own electricity.”

Cuba Libre Restaurant & Rum Bar, 801 Ninth St., NW; 202-408-1600.

Open Monday through Friday for lunch (starting October 20) and dinner, Saturday and Sunday for brunch (starting October 23) and dinner. Dinner appetizers $5 to $19, entrées $16 to $32. Through October 7, dinner is 50 percent off; October 8 through 14, it's 25 percent off.